Telephone system



Feb. 15, 1944. s. E. FETERSON ETAL 2,341,879

TELEPHONE sysmw I Filed April 16, 1942 1'? sheets s heej. 3

H65 FINDER SELECTOR LINK l5 -n-E2QZ&- as2 L INE R330 W320 R340 [3360 V T INVENTORS SETH E. PETERSON BY VINCENT A-JOHNSON w. My M m E M S 's. E. PETERSON '21- AL TELEPHONE SYSTEM Filed April 15, 1942 Feb. 15, 1944. v 2,341,879

17 Sheeis-Sheet 4 FINDER SELECTOR LINK l5 gizJzac PULSING TO REVERTIVE PULSE RELAYS INVENTORS SETH E.PETERSON BY V|NCE NTA.JOHNSON ATTORNEYS Feb. 15, 1944.

- FIGS 17 Sheets-Sheet 5 REGISTER SELECTOR l8 35b; If,

55a 35 j N a 3661 W isss 35d 5362 Rm 560a L ALL BUSY D- TO OTHER LOCKOUT N VENTORS VINCENT A. JOHNSON ATTORN EYS Feb. 15, 1944.

s. E. ETERSEN ETAL TELEPHONE SYSTEM Filed April 16, 1942 17 Sheets-Sheet 7 ATTORNEYS Feb. 15, 1944 s PETERSON ET AL 2,341,879

TELEPHONE SYSTEM Filed April 16, 1942 17 Sheets-Sheet 8 FIG, 8 REGISTER" SENDER l9 aol 5 3 834 M INVENTORS SETH E. PETERSON BY VINCENT A. JOHNSON fi--gfi d m ATTORNEYS Feb. 15, 1944. s. E. PETERSON E TAL 4 TELEPHONE SYSTEM Filed April 16, 1942 17 Sheets-Sheet 9 F 16. 9 RGISTER SENDER,19

Qumoms D coumms 9n SWITCH REV. CA 925/ 9 5 TWO VDIGIT DIGIT R I REV INVENTORS SETH E. PETERSON BY VINCENT A.-JOHNSO.N

'QW,W,M 9m ATTORNEYS 1944- s. E. PETERSON, ET AL 2,341,379

' TELEPHONE SYSTEM V v Filed.April 16, 1942 17 Sheets-Sheet 1i I v REGISTER SENDER l 9 IIIO mcomms men co UNTI N s SWITCH noo KIIOS I04 ATTOR hEYS Feb. 15, 1944. s, EQ ETE RS N ETAL 2,341,879

TELEPI IO NE SYSTEM r 4 3 'Filed April 16, 1942 '17, Sheets-Sheet :12

RE .ER SENDER: l9

F l G. [2

TERMINAL ROW l DP DPM TERMINAL- ROW 2 I TERMlNAL ROW 4 secouo 4 men GONNEGT lN-VENTOR. SETH E. PETERSO -VINC ENT A.JOHNSON J Feb. 15, 1944. s. E. PETERSON ETAL 2,341,379

TELEPHONE SYSTEM Filed April l6, 1942 17 Sheets-Sheet l5 I IM f0 FlGja I PuLs a s r w s RELAYS REGISTER SENDER I9 INVENTORS SETH E. PETERSON VINCENTA .JOHNSON WW ,M m

ATTORNEYS 4 s. E. PETERSON ETAL 2,341,379

TELEPHONE SYSTEM Filed April 16, 1942 IMPULSE STORING'RELAYS 1'7 Sheets-Sheet 14 GROUP N0. 2

FIG. l4

2 K 4 11 .m 0 x w H R 5 ia\ \Mn Tv T O x 2 0 mi ma 4 O O O 4 4 4 II II 1 W x d. SPZ l SH2 W R m E s m T 5 G E R INVENTORS SETH E PETERSON VINCENT A. JOHNSON r M. M M ATTORNEYS Feb; 15, 1944. a E, isETERsoN ET 2,341,879

TELEPHONE SYSTEM Filed'April 16, 1942 17 Sheets-Sheet 15 IMPULSE FIG. l5 gggwgg RELAYS 1500 -R|s|o I520 RISBOI Rl540 "R550 REGISTER SENDER l9 ENTOR SETH E. PE P RSON s YVINGENT'AJOHNSGV MM M m I ATTORFEYS Feb. 15, 1944. s. E. PETERSON ET AL 4 ,3

TELEPHONE SYSTEM Filed April 16, 1942 17 Sheets-Sheet 16 FIG. l6-

CONNECT IMPULSE COUNTING RELAYS REGISTER SENDER l9 INVENTORS SETH E. PETERSON A BY vmcsu'r uomson ATTGR'NEIS Feb. 15, 1944. s. E. PETERSON ETAL' v 2,341,379

TELEPHONE SYSTEM Filed April 16, 1942 I 17 Sheets-Shat 17 FIG]? IMPULSE SENDING RELAYS A asuzngse June I M152 me Rl720 W r-' r174: 5 2 151 SENDING I753 him I730 Bil-(I140 F WIS A M V 1 L M? REGISTER ssuoaa l9 R|7OO PULSE s E NE RATOR W 5 sTARr -33 NOV VINCENT A.JOHNSON ATTOR EYS Patented Feb. 15, 1944 TELEPHONE, SYSTEM Seth E. Peterson, Bogota, Colombia, and Vincent A. Johnson, Evanston, Ill., assignors to Automatic Electric Laboratories, 1110., Chicago, 111., a corporation of Delaware Application April 16, 1942, Serial No. 439,218

78 Claims.

In efiecting a system conversion of the characterindicated, it is economically desirable to utilize, so far as possible, the installed switchgear of the semi-automatic system with but a minimum of changes in the arrangement thereof. switchgear of the system must be so modified that the register senders of the system may be directively controlled from the calling substations rather than from an operator position; and that the register senders themselves must be completely reorganized to accept dial pulses received from the calling substations and automatically to render services previously handled by an operator. It may also be desirable in efiectinga system conversion of this character to add new directively controllable automatic switching equipment or to replace existing equipment of this form with new equipment. The new or added equipment may or may not be arranged for the same type of directive control by the register senders as the existing equipment. For example, the existing switching equipment may be arranged for revertive control oi the register send-- ers during a call forwarding operation, while the new or added equipment may be arranged to receive switch directing pulses directly from a reg ister sender during a call forwarding operation without exercising any control whatever over the impulse sending equipment of the register sender in use. This means that the register senders provided in the converted system must be equipped to furnish two or more types of directive control of the automatic switching equipment and that the register sender used in forwarding any given call must be equipped to switch. from one type .of directive control to the other after the call has progressed to a given switching/stage. Moreoventhe newautomatic switches may be added at different switching stages of the system so that in forwarding difierent calls the change from one type of directive control to the other must be efiected in the register senders In practice, this means that the existing after diiierent numbers of the digits registered therein have been utilized in the directive control of the switching equipment.

It is an object of the present invention, therefore, to provide improved facilities for converting a telephone system of the semi-automatic type into a system of the fully automatic type with but a minimum number of changes in the existing equipment and with the addition of a minimum amount of new equipment.

According to another object of the invention, an improved arrangement is providedwhereby the directory number designations produced under the control of a calling device locatedat a calling substation may be transmitted to the register sender occupied with a call at a point preceding the first directively controlled switching stage of thesystem.

According to a further object of the invention, an improved arrangement is provided for looking out of service the links having access to the calling lines of the system whenthe register senders to which these links have access areall busy.

Itis a further object of the invention to provide for use in a systemof the character described, improved register senders which are so arranged that the installed automatic switching equipment of the system may be retained with but slight modification thereof and new equipment of the same or a difi'erent type may be added to the system as required.

According to another object of the invention, each register sender is arranged to exercise either of two types of directive control over the associated automatic switches, and the character of the directivecontrol exercised thereby in forwarding a call to its destination is automatically adapted to the type or types of directive control required by the automatic switches through which the call must be routed.

In accordance with another object of the invention, each register sender is equipped with facilities controlled in accordance with the numerical value of one of the digits transmitted to the register sender during a directory number dialing operation for automatically setting the type pattern for the directive control of the automatic switches through which the call must be extended.

It is another object of the invention to provide register senders which are each equipped with improved facilities for transmitting to a calling substation those signals which are commonly utilized to enable thecalling subscriber to follow the progress of a call;

l According to another object of the invention,

According to still another object of the invention, each register sender is equipped automatically to transmit a ring-back tone signal to a calling substation immediately after the dialing operation is completed at the calling substation and before the sender has completed its operation to direct the call through the associated switching apparatus to the called line.

According to still another object of the invention, each register sender is provided with facilities for automatically withholding from the associated switching equipment the last digit of a received reverting call directory number until the calling party hang up his receiver.

In accordance with a further object of the invention, the facilities provided in each register sender for withholding the last digit of a received reverting call directory number and for transmitting the required signals over the line occupied with the reverting call, are conditioned for operation by transmitting to the register sender a predetermined prefix digit which identifies the character of the call.

It is a still further object of the invention to provide for use in a converted systernof the character described, an improved register sender which is equipped with facilities controlled in accordance with the numerical value of one of the digits of a received plural digit directory number for indicating the number of digits of the directory number.

According to another object of the invention, provisions are made in the register sender for automatically releasing the sender afterthe in- .dicatednumber of digits have been transmitted therefrom to the associatedautomatic switching apparatus. v In accordance with still another object of the invention, the register sender is equipped with facilities for rendering the digit registers of the sender non-responsive to received impulses after the indicated number of digits have been received.

, The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings in which Figs. 1 to 17, inclusive, when laid side by side in numerical order, illustrate a telephone system characterized by the features of the invention briefly referred to above.

Referring now more particularly to the drawings, the telephone system there illustrated comprises a central exchange which terminates a number ofsubscriber lines and may be trunkconnected to a number of smaller exchanges, certain of which may be of the fully automatic type. The centralexchange is illustrated as terminating two subscriber lines I and H, the first of which is of the multiparty type serving the substations A and E and the last of which is of the single party type serving only the substaup local connections between the subscriber lines terminated at the central exchange, and of handling certain interexchange calls in the manner more fully pointed out below, the central exchange is equipped with automatic switching equipment which, in the main, may comprise automatic switches previously in use when the exchange was operated on an auto-manual basis.

In brief, this equipment comprises a plurality of groups of finder-selector-links, one of which includes the link I5, shown in Figs. 2, 3 and 4 of the drawings; a plurality of groups of second selectors, two of which respectively include the selectors l6 and 2t; and a plurality of groups of connectors, one of which includes the connector [1. Each group of finder-selector-links is arranged to serve a particular group of one hundred subscriber lines and has associated therewith a link distributor and common equipment. Thus the lines It! and I l are illustrated as being served by the link group which includes the link I 5.

This group of links has associated therewith a' link distributor and common equipment of. conventional form, schematically indicated at M. For the purpose of directively controlling the indicated automatic switches of the central exchange, a plurality of groups of register senders are provided therein, the various groups being individual to the diiferent groups of finderselector-links. Thus the illustrated register sender IQ of Figs. 6 to 17, inclusive,'is shown as being included in the sender group associated with the group of links in which the link I5 is included. In order operatively to associate an idle one of the register senders with a link to which a call is extended, each of the links has associated therewith a register selector that has access only to the register senders of the associated sender group. Thus the link [5 is shown as having associated therewith a register selector l8 which has access to the register senders in the group including the register sender I9.

The directively controllable selectors of the finder-selector-links, the second selectors and the connectors provided in'the central exchange may all be a part ofthe switching equipment installed in the exchange prior to its conversion from an auto-manual system to a fully automatic system. As is commonly the practice in most of the installed exchanges of this character, each of these directively controllable switches is arranged for revertive control of the register senders or register markers initially provided in the exchange for directing these switches in their operation to extend connections therethrough. Accordingly, each of the register senders provided in the'exchange as converted is arranged in the novel manner. more fully described hereinafter to provide this type of directive control in extending connections through the original switchesof the exchange.

As a necessary adjunct of the conversion, it may occur that the subscribers served by the central exchange are to be provided with free service to the subscribers served by other automatic exchanges in which the automatic switch,

sive to received dial impulses. Alternatively, it may be expedient in modernizing the equipment of the central exchange to replace certain of the switches beyond the first directively controlled switching stage with automatic switches which are arranged to respond directly to received dial impulses. In order toillustrate these possibilities, the system is shown as comprising a four digit direct pulse connector 2| which is accessible to the selector portion of the link l5 and has access to a line l2 extending to the substation C. This connector may, for example, be of the all-relay type disclosed in copending application Serial No. 344,870, filed July 11, 1940, John H. Voss, and may be located in a distant smaller exchange. As installed, it is, of course, preceded by a non-numerical finder switch and the usual runk repeaters, as indicatedby the dash lines inserted in the trunk 24 incoming thereto. For

reasons which will become apparent as the description proceeds, this connector is provided with facilities for absorbing a received first digit of nine impulses. Further to illustrate the two possibilities mentioned above, the revertive pulse second selector is shown as having access to a four digit direct pulse switch train 22 over the trunk 26. This switch train is also arranged to respond directly to received dial impulses and may be provided in an exchange of the fully automatic type remote from the central exchange under consideration. It may, for example, comprise an incoming selector which has access to a three digit comiector through which connections may be routed to the line l3 serving the substation D.

The finderselecto1-links provided in the central exchange are identical in arrangement. Briefly considered, the illustrated link l5 comprises a finder switch of the all-relay type, a selector switch of the two-motion step-by-step type, and a group of control relays. More specifically, the finder switch comprises ten group relays, each of which is individual to the lines forming a ten line subgroup, and ten unit relays each of which is individual to a particular line in each subgroup, Th illustrated group and unit relays R2) and R220 are shown as having contacts through which the conductors of the line it may be connected to the control equipment of the link. The selector switching mechanism of the link is of the type wherein the Wipers are first rotated under the control of a rotary magnet and then elevated under the control of a vertical magnet. In brief, this mechanism comprises a contact field which is divided into eleven contact levels; wipers 410 to 413, inclusive, for making connections with the contacts in any desired contact set; a rotary magnet 414 for rotating the enumerated wipers to positionsame opposite a desired vertical row of contacts; a vertical magnet 115 for elevating the wipers to a position wherein they engage the contacts forming the desired contact set in the selected vertical row; a release magnet 415 which, when energized, permits the enumerated Wipers to be returned to vertical and rotary normal; vertical off-normal springs 411, 418 and 419 which are operated away from the illustrated normal positions thereof when the enumerated wipers are moved off-normal in the vertical direction; and rotary off-normal springs 480 which are moved into engagement when the enumerated wipers are rotated away from the normal positions thereof. The relay equipment provided in the link comprises, in addition 'to :th finder group and unit relays, a start relay-R200, a marginal lockout relay R230, a switching relay R300, 5, linerelay R330, a slow-acting release relay R400, a trunk hunting relay R430, a slow-acting trans fer relay R440, a revertive pulse relay R450, a pulsing relay R450, and nine additional control relays R240, R250, R3l0, R320, R340, R350, R360, R410 and R420. The link also comprises an impedance element 335 having an impedance which balances that of the line relay R330 after a connection has been established between the talking conductors of the link and the conductors of a calling line. A permanent signal lamp 255 is also provided therein whichis controlled in the manner more fully explained below to indicate that the link has been locked out of serv? ice and is thus non-accessible to the lines associated therewith.

The register selectors individually associated with the finder-selector-links are also of identical arrangement. In brief, the illustrated register selector I8 comprises a selecting switch 550 of the well-known rotary type, a line relay R520, a test relay R530, and a control relay R5l0. More specifically, the switch 550 comprises four sets of contacts 551, 552, 553 and 554 of ten points each, wipers 556, 551, 5-58 and 559 individually associated with the enumerated contact sets, and an operating magnet 560 for driving the indicated wipers over the contacts of their respectively associated contact sets.

The register senders accessible to the register selector I0 and the other register selectors in the same group have commonly associated therewith an all-busy relay R500 which is arranged to control one or more lockout relays R540. These relays are provided for the purpose of indicating an all-busy condition of the register senders in the associated sender group and function to prevent useless seizure of the associated finder-selector-links during a period when no register senders are available for controlling the links to extend connections therethrough.

The register senders provided in the central exchange are also identical in arrangement.

Briefly considered, the register sender is comprises three digit registers or groups of storing relays, respectively illustrated in Figs. 13, 14 and 15 of the drawings as including six relays per group; a group of impulse counting relays, shown in Fig. 16 of the drawings as including the relays Rl630, Rlfi lil, R5650, RIE50, more and RI680; three slow-acting connect relays R1600, Ri6l0 and RI 520 for successively associating the storing relay groups with the counting relays; and a group of impulse sending relays through opera.- tion of which the digits set upin the storing relay groups and transferred to the counting relays are transmitted from the register sender. The last-mentioned group of relays includes a change pulse relay R3100, a slow-to-operate start relay Rl1l0, a slow-to-operate release relay R1120, a pair of pulsing relays R| and Ri100, and a pair of control relays R5130 and R1140, the last of which is of the slow-to-operate type. This group of relays together with the corresponding relays of the other register senders have commonly associated therewith a pulse generator 33, which may be of any desired type well known in the art.

The register sender 59 further comprises an incoming digit counting switch H00, having the function of successively directing the received digits of a plural digit directory number to the three groups .ofstoring relays; .an outgoingdigit 

